This is a statistically-sound poll. From my survey sampling and experimental design experience, this was well-conducted.

Maybe the methodology was sound, but to take the results of that poll and say that they mean that "87% of Americans want expanded background checks" is BS. The problem is with the question:

"Do you support or oppose legislation that would require background checks for private gun sales and sales at gun shows?"

We already have legislation that requires background checks on all dealer sales, including all dealer sales at gun shows, which compromise the vast majority of sales at gun shows.

We also already have legislation that requires anyone shipping a gun in a private sale (like all "online" sales) to ship the gun to a FFL holder, who will run a background check if the purchaser does not hold a FFL.

I'm in support of that legislation. If I were being truthful in my response to that question, I would have to answer "yes". However I was strongly opposed to all of the legislation being voted on yesterday.